Operators usually offer an “Internet Access” service via a so-called default bearer. The default bearer enables packet transmission between a User Equipment (UE) and a gateway. User differentiation for a default bearer may be possible; that is, the service level of a particular user's default bearer could be “gold”, “silver”, or “bronze” based on a user's subscription data with the service.
In 3G networks the connection to an IP network is offered trough the use of bearers such as a PDP context or a Service Architecture Evolution (SAE) bearer. A bearer is a point-to-point connection from the user terminal to the IP network provided by either the operator or an Internet Service Provider (ISP). For each bearer it is possible to specify a Quality of Service (QoS) profile. The QoS profile contains parameters such as peak throughput, mean throughput, delay, and reliability.
It is also possible to activate more than one bearer for a given user. A bearer may be either a primary bearer or a secondary bearer. A primary, or default, bearer has a unique IP address assigned, while a secondary, or dedicated, bearer has the same IP address as the primary bearer if the secondary bearer is activated. The secondary bearer normally has a different QoS profile than the primary bearer. The primary bearer is typically activated to different Access Point Names (APNs), while the secondary bearer is connected to the same APN as the primary.
A typical scenario where a primary and a secondary bearer are activated is when there are both UDP and TCP traffic. A primary bearer with low reliability may be activated for the UDP traffic, and a secondary bearer with high reliability may be activated for the TCP traffic. Another scenario is a multimedia streaming session, in which there is one bearer with high throughput for the payload, and a second bearer with different characteristics for signaling.
When more than one PDP bearer is established for a user, different packets may be handled with different QoS and should therefore be put onto the correct bearer. Traffic from a Gateway GPRS Support Node (GGSN) towards the UE is put onto the correct bearer through the use of packet filtering specified by a Traffic Flow Template (TFT) (defined by 3GPP in Technical Specification 23.060). Each bearer can have a TFT specified. A TFT may contain up to eight packet filters, and each packet filter may contain attributes such as protocol number, source or destination port, or source IP address (and more). If a packet enters a downlink bearer, the packet must match at least one of the packet filters in the TFT.
FIG. 1 is a high level block diagram of an existing network configuration for directing downlink traffic to the correct PDP context or bearer. A Gateway GPRS Support Node (GGSN) 11 receives packets through an ISP connection 12. When more than one bearer is established, different packets may be handled with different QoS and the GGSN must put them onto the correct PDP bearer (for example, Context1 13 or Context2 14). The downlink packets are put onto the correct bearer through the use of packet filtering specified by Traffic Flow Templates (TFTs) 15 and 16 (defined by 3GPP in Technical Specification 23.060). Each TFT is associated with a particular bearer. A TFT may contain up to 8 packet filters, and each packet filer may contain attributes such as protocol number, source or destination port, or source IP address (and more). The ISP connection 12 provides the entire downlink flow to each TFT, and each TFT determines which packets meet the filter attributes for its associated bearer. A packet must match at least one of the packet filters in the TFT in order to enter the associated downlink bearer for transmission to the mobile station (MS) 17. Otherwise, the packet is dropped.
A problem arises when trying to configure the TFTs in the GGSN for downlink packet traffic. The TFTs must be configured manually prior to context activation, and if the TFTs are set static for the context, there may be some applications that have a behavior requiring the TFTs to be more dynamic. If the TFTs are set too general (broad), packets not belonging to the bearer may be allowed to enter, and if the TFTs are set too specific (narrow), packets belonging to the bearer may be rejected. Depending on the kind of traffic flowing, the packet attributes can be quite dynamic, which can lead to a need to use a broadly defined packet filter.
It would be advantageous to have a system and method for dynamically configuring TFTs that overcomes the disadvantages of the prior art. The present invention provides such a system and method.